to NICO! With a gas smell that bad, I wonder if your car won't start because it's hydrolocked? It's worth checking before you spend any more money on parts.
How much do you trust your mechanic's diagnosis? Codes from these old OBD1 ECUs can be more of a starting point than a true "here's what's wrong" issue. The part number for your sensor should be 2268061U00. Confirm that you have the square connector, and not the rounded one. I can't remember when they made the switch (mid 1994 or mid 1995?).
Your best bet is eBay, or www.car-part.com
- also check our classifieds here at NICO.